Jul 23, 2009 -- Kabul - Two foreign fighters were among 13 Taliban insurgents killed in an offensive in northern Afghanistan involving mainly German troops along with Afghan government forces, the provincial governor said Thursday.

The joint Afghan army, police and German forces 'cleared Chardarah district of Taliban and al-Qaeda forces yesterday evening,' Mohammad Omar, provincial governor of the northern province of Kunduz, where the operation is taking place, told the German Press Agency dpa.

On the sixth day of the assault, the combined forces began their operation in Gor Tape, some 18 kilometres from the capital city, also called Kunduz, on Thursday morning, the governor said, adding that 'so far 13 Taliban militants, including two Chechen, have been killed in the fighting.'

A dozen more militants were wounded in the operation, while 13 fighters were detained by the combined forces, Omar said. He said the militants were killed and wounded on Tuesday and Wednesday.

'So far the Afghan and German forces are making a good advance in the Gor Tape area and there is no resistance from the Taliban side in the area,' he said.

The operation is being jointly conducted by 300 German troops, 800 Afghan army soldiers and 100 Afghan police in the relatively peaceful Kunduz, where the militants have recently increased their presence and activities.

Four Afghan army soldiers have also been killed in the operation and two others were wounded, General Zahir Azimi, spokesman for the Afghan Defence Ministry, told dpa, adding that a Taliban commander, Mohammad Rasoul, who was famous for his expertise in making roadside bombs, was also among the 13 militants killed.

Azimi said that the operation would continue until the combined forces drive all the militants from the area and make the province a safer place before the August 20 presidential election.

'This time the Afghan army and police forces will remain in the districts after the Taliban are kicked out,' he said.

Several Afghan civilians, most of them schoolboys, were also killed in Char Darah district after a Taliban rocket landed in their religious school on Tuesday, Omar said.

Local Afghan media, quoting local residents, said 13 civilians died in the attack, but Omar said that the exact death toll would be announced after the completion of an ongoing investigation.

The Taliban announced earlier this year that they planned to expand their area of military operations from their main hub in volatile southern and eastern regions to relatively peaceful northern and western provinces. The militants have conducted most of their attacks in the southern and eastern regions in the past eight years since the ouster of their regime.

Afghan officials believe that the recent agreement between the United States and Russia to allow coalition supplies to pass through Russia could have persuaded the Taliban to increase the number of their fighters in the northern region.

'I am sure the Taliban want to strengthen their presence in the northern region to be able to attack the logistics convoys of international forces and to disrupt the upcoming election,' Omar said.

The US and other NATO partners have been trying to find an alternative supply route after their logistics convoys repeatedly came under attack in Pakistan over the past year. Landlocked Afghanistan depends on its neighbours to access the ocean.

Germany has around 3,700 soldiers in northern Afghanistan, serving with a 65,000-strong NATO-led force deployed to the country from 42 nations.

Three German soldiers were killed in a firefight with the Taliban in June, bringing to 35 the number killed since initial deployment in 2002.